<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        function ajax() {
            return new Promise((resolve, reject) => {
                resolve("data-111")
            })
        }
        //显示loading
        ajax().then(data => {
            console.log(data)
        }).catch(err => {
            console.log(err)
        }).finally(() => {
            console.log("finally")
            //finally不管成功还是失败都会执行
            //这里做一些隐藏loading，关闭缓存，关闭对话框等等
        })
    </script>
</body>

</html>